Production of graphene using electromagnetic radiation

Abstract

Methods for converting graphite oxide into graphene by exposure to electromagnetic radiation are described. As an example, graphene oxide may be rapidly converted into graphene upon exposure to converged sunlight.

What is claimed is: 
     
       1. A method of converting graphite oxide to graphene, the method comprising:
 focusing sunlight to produce focused sunlight; 
 exposing graphite oxide having a first conductivity state to the focused sunlight for a period of time sufficient to convert at least a portion of the graphite oxide into graphene having a second conductivity state, wherein the second conductivity state is higher than the first conductivity state; and 
 wherein the focused sunlight is incident on the graphite oxide at an intensity from about 0.5 watts/cm 2  to about 7 watts/cm 2 . 
 
     
     
       2. The method of  claim 1 , wherein the focused sunlight comprises one or more wavelengths from about 250 nm to about 2,500 nm. 
     
     
       3. The method of  claim 1 , wherein focusing sunlight comprises passing the sunlight through at least one refractile material prior to the exposing step to increase the intensity of the sunlight. 
     
     
       4. The method of  claim 1 , wherein focusing sunlight comprises passing the sunlight through at least one converging lens prior to the exposing step to increase the intensity of the sunlight. 
     
     
       5. The method of  claim 1 , wherein focusing sunlight comprises reflecting the sunlight off of one or more converging mirrors to increase the intensity of the sunlight. 
     
     
       6. The method of  claim 1 , wherein the graphite oxide comprises dry graphite oxide. 
     
     
       7. The method of  claim 1 , wherein the exposing step heats the graphite oxide to a final temperature at a rate of at least about 100° C. per second for less than about 2 seconds, and maintains the final temperature for the remainder of the step. 
     
     
       8. The method of  claim 1 , wherein the exposing step heats the graphite oxide to a temperature of less than about 200° C. 
     
     
       9. The method of  claim 1 , wherein the exposing step is performed for no more than about 10 minutes. 
     
     
       10. The method of  claim 1 , wherein the exposing step is performed for no more than about 5 minutes. 
     
     
       11. The method of  claim 1 , wherein the first conductivity state is less than about 10 −3  S/m. 
     
     
       12. The method of  claim 1 , wherein the first conductivity state is about 10 −5  S/m. 
     
     
       13. The method of  claim 1 , wherein the second conductivity state is greater than about 1,000 S/m. 
     
     
       14. The method of  claim 1 , wherein the second conductivity state is greater than about 1,400 S/m. 
     
     
       15. The method of  claim 1 , wherein the graphene has an oxygen content less than about 5% by weight. 
     
     
       16. The method of  claim 1 , wherein a Raman spectrum of the graphene comprises bands at about 1360 cm −1  and about 1570 cm −1 , and the intensity of the band at about 1360 cm −1  is less than or equal to about half the intensity of the band at about 1570 cm −1 .